by Mica Rosenberg and Jeff Ernsthausen

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The chief of police in Whitewater, Wisconsin, didn’t ask for the moon in late 2023 when he wrote to President Joe Biden about the hundreds of new Nicaraguan migrants who’d arrived in his city over a whirlwind span of two years. All of a sudden, he wrote, his 23 sworn officers were dealing with three times the number of drivers without licenses on local roads.

Biden administration officials didn’t get back to the chief for almost two months. And when former President Donald Trump learned about Whitewater’s predicament, he seized on it as further evidence that the United States was being overrun by “migrant crime” and promised voters he would conduct the “largest deportation in American history,” though that’s not at all what the chief was asking for, much less how he saw his city.

The small Wisconsin town is one of a number of American communities that have experienced the strains of a new phase of immigration whose origins and meaning have been obscured during this year’s presidential election by Trump’s incendiary rhetoric and the reluctance of his opponent, Vice President Kamala Harris, to clearly address the Biden administration’s track record on the issue.

In the coming days, ProPublica will publish a series of stories that we hope will be of use to voters, especially those focused on immigration as a key issue. We aim to provide a more complete picture of what’s happening on the border and in cities and towns across the United States. Amid the misleading bombast of the campaigns, our reporting on the ground and analysis of government data will explain the real challenges — as opposed to the ones being made up to scare you — posed by immigration trends at the Southwest border over the past decade.

We’ve found that what’s changed most about the border isn’t just the number of migrants coming across. It’s who’s coming and how. Many of today’s migrants are coming from new places and in new ways that make their arrivals more visible and, at times, more costly to the communities where they settle. And those changes are coinciding with, if not helping drive, a hardening in public opinion.

Our analysis of immigration court and census data found that while the number of times U.S. officials encountered migrants at the border spiked in the past three years, only a small share of Americans live in neighborhoods that saw a significant number of new arrivals when compared with their populations. We found that migrants were concentrated in relatively few places around the country.

In places like Whitewater that were ill-prepared for those increases, the new arrivals created small pockets of upheaval that, thanks to television and the internet, spilled into the public consciousness. Meanwhile in large Democratically controlled urban centers like New York and Chicago, where migrants have settled for generations, the new arrivals _— including some bused north by Republican governors seeking to make political points — strained resources in ways that set off flashes of resentment.

In Denver last year, taxpayers watched their city government provide months of free housing to Venezuelan migrants, while many in its long-standing homeless population languished on the streets. In Belle Glade, Florida, a farmer who’d long depended on immigrant labor had a change of heart after he became a state lawmaker, helping pass restrictions against hiring undocumented workers.

And at the border, in Del Rio, Texas, residents who had long been accustomed to the rhythms of crossings between the U.S. and Mexico were shaken by the swift and sudden arrival of nearly 20,000 predominantly Haitian migrants — a number that amounts to more than half the local population. Three years later, residents fear that such a destabilizing event could happen again. One Democratic candidate for sheriff there has taken positions so openly critical of his own party that local Republicans invited him to join their side.

More migrants crossed the border without getting caught in the early 2000s. But today’s migrants are more likely to turn themselves in to authorities, often seeking asylum.

Public opinion polls show that concern and confusion about immigration persist among Americans beyond Del Rio. To understand why, consider the chart Trump shared with his supporters during a rally in July in Butler, Pennsylvania. It showed the numbers of migrants encountered at the Southwest border over the past decade. Trump turned to it in the split second a would-be assassin’s bullet grazed his ear. He says he loves the chart, even gushing about sleeping with it, because it probably saved his life. But the reason he’s continued to display it at subsequent rallies is that it shows the record jump in encounters that occurred under Biden and Harris, which he says is evidence of the administration’s failure.

What Trump doesn’t say is that the increase actually began while he was still in office. Meanwhile, Harris has touted the tough asylum restrictions the Biden administration has imposed this election year that have led to dramatic decreases in the number of illegal crossings. But she doesn’t talk about why it took so long to do so. And she says even less about how some of her own allies accuse her of adopting immigration proposals they say are similar to Trump’s.

Voters could be forgiven for not knowing whom to believe, for feeling there is an unprecedented crisis at the border. But in past years, according to government estimates, there were many more migrants who........

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